ServerNet Cluster 6780 Planning and Installation Guide (G06.24+, H06.03+)

Configuring Expand-Over-ServerNet Lines
ServerNet Cluster 6780 Planning and Installation Guide—527301-004
7-3
Rule 1: Configure the Primary and Backup Line-
Handler Processes in Different Processor
Rule 1: Configure the Primary and Backup Line-Handler
Processes in Different Processor Enclosures
Whenever possible, configure the primary and backup Expand-over-ServerNet line-
handler processes in different processor enclosures. This rule applies to all systems
except for two-processor systems, which have only one processor enclosure. Rule 1
takes precedence over Rules 2 and 3.
Rule 2: For Nodes With 6 or More Processors, Avoid Configuring
the Line-Handler Processes in Processors 0 and 1
Whenever possible, avoid configuring Expand-over-ServerNet line-handler processes
in processors 0 and 1. Key system processes, such as $SYSTEM, can run only in
processors 0 and 1. By reducing the number of processes using processors 0 and 1,
you can minimize the risk of key system processes undergoing a software halt.
Because Rule 1 takes precedence over Rule 2, Rule 2 can be applied only in nodes
having three or more processor enclosures. In a node with two processor enclosures,
the line-handler process pair must be configured following Rule 1. Therefore, either the
primary or the backup must run in processor 0 or 1.
Rule 3: For Nodes With More Than 10 Processors, Avoid
Configuring the Line-Handler Processes in Processors 10
Through 15
Whenever possible, avoid configuring Expand-over-ServerNet line-handler processes
on processors 10 through 15. There are more ServerNet components (routers and
links) along the paths from these processors to the external fabrics than along the
paths that originate in the inner tetrahedron (processors 0 through 7) or processors 8
and 9. Consequently, these paths have a higher probability of failing as a result of
hardware faults.
Expand-Over-ServerNet Line-Handler Process Example
The Expand-over-ServerNet line-handler process is similar to the Expand-over-FOX
line-handler process. However, for Expand-over-ServerNet lines, you configure a
subtype code of 4 and use the PEXPSSN profile. The ASSOCIATEDEV parameter
contains the name of the SNETMON process, $ZZSCL.